Device and method for depositing sheet-shaped substrates so as to form a stack

ABSTRACT

The present invention relates to a device and a method for depositing sheet-shaped substrates ( 6 ), in particular printing materials, in a printing machine so as to form a stack. The device comprises a tray ( 10 ) for receiving the substrates, said tray having a tray surface ( 8 ) that is tilted about a first axis and about a second axis, relative to a horizontal. Also provided are a lifting device for lifting and lowering the tray, as well as a first abutment having a first abutment surface and a second abutment ( 26 ) having a second abutment surface, with the first and the second abutment surfaces being arranged so as to be perpendicular to each other, and with substrates deposited on the tray coming to abut against the first and the second abutment surfaces due to the tilting of the tray surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of prior U.S. patent application Ser. No. 13/377,836, filed Dec. 13, 2011, which is a U.S. patent application Under 35 U.S.C. 371 of International Patent Application No. PCT/EP2010/58614, filed Jun. 18, 2010, (published as WO 2011/000717 on Jul. 7, 2011) each of which are hereby incorporated herein by reference in their entirety.

The present invention relates to a device for depositing substrates and to a method for depositing sheet-shaped substrates, in particular printing materials, in a printing machine so as to form a stack.

In printing technology, it has been known to print sheet-shaped substrates and to subsequently deposit them so as to form a stack on a height-adjustable tray. To do so, the substrates are usually transported so as to be at a certain distance above the tray or the uppermost sheet of a stack on the tray and are then released, as a result of which the sheet falls down. It is known to provide the tray with a slope that is inclined counter to a transport direction of the substrate in order to enable the substrates so slide against an abutment in order to form a defined stack edge in transport direction of the substrates. Furthermore, it is known to provide lateral abutments on the tray, said abutments being intended to also provide an alignment of the stack in lateral direction. For example, systems comprising lateral guides are known, where said lateral guides can be moved toward each other and away from each other in order to compress a substrate stack between them and, in turn, to release said stack, thus creating a defined lateral stack edge. However, such systems are only suitable for smaller stacks that allow the needed compression. In addition, such systems are associated with high costs and are susceptible to trouble.

Also known are systems working with lateral guides, along which the substrates slide when they are being ejected and which are intended to, thus, convey the substrate into a predefined position. However, systems of this type have the disadvantage that their guiding accuracy is limited by the necessity of having to always adjust the inside width between the lateral guides so as to be greater than the nominal format width. Reasons for this are cutting tolerances of the substrate as well as the conveying deviations of individual sheets in the direction transverse to the transport direction which are caused by the printing machine.

Consequently, when substrates are output in known systems, stacking inaccuracies in the direction transverse to the substrate transport direction occur frequently. Different disturbances such as, e.g., a skewed alignment, also referred to as skew, electrostatic charges, bending of the substrates, also referred to as curl, as well as friction between the substrates, additionally affect accurate stacking in a disadvantageous manner, with light-weight sheets being affected more than heavier-weight sheets. Consequently, the object of the present invention is to create a device and a method for depositing sheet-shaped substrates, said substrates covering a wide range of substrates, with increased stacking accuracy, in particular in a direction transverse to the substrate transport direction, so as to form a stack on a tray.

In accordance with the invention, this object is achieved by a device in accordance with claim 1 and by a method in accordance with claim 21. Additional embodiments of the invention result from the respective subclaims.

In particular, a device is provided for depositing sheet-shaped substrates, preferably printing materials, in a printing machine so as to form a stack, said device comprising a tray for receiving the substrates and comprising a lifting device for lifting and lowering said tray. The tray has a tray surface that is tilted about a first axis and about a second axis, relative to a horizontal. Furthermore, the device has as a first abutment with a first abutment surface and a second abutment with a second abutment surface, the first and the second abutment surfaces being arranged so as to be perpendicular to each other, and substrates deposited on the tray coming to abut against the first and the second abutment surfaces due to the tilting of the tray surface.

Using a simple design, such a device allows a high stacking accuracy because the alignment takes place on two abutments that are arranged perpendicularly with respect to each other. One advantage of such substrate stacks is that they can be processed further without any intermediate steps. Further processing of the substrate stack may comprise binding of said stack, for example. Due to the appropriate double inclination of the tray, the substrates automatically move against the abutments, without requiring the use of expensive and complex mechanical systems. By lifting and lowering the tray, it is possible to maintain an essentially constant dropping height of the ejected substrates on the stacks. The trays may be lifted and lowered in different ways. For example, it is possible to lower the tray by a certain distance after each ejection of a substrate sheets. Further, it is possible to lower the tray by a corresponding greater path distance, after each ejection of a prespecified number of substrate sheets.

In one embodiment of the invention, the first axis is parallel to a printing material transport axis, and the second axis extends perpendicularly to the first axis and is in a plane parallel to the tray surface.

Preferably, the device comprises a gas supply arrangement having a gas outlet opening that is directed at the lowest point of the support surface. The support surface may be the tray surface itself, on the one hand, or the substrates already on the tray surface, on the other hand. The gas supply arrangement is disposed to guide a gas stream at the tray plane or the substrate surface in order to ensure a friction-reducing sliding of the sheet-shaped substrates against the abutments. In addition, the substrates are also carried along by the gas stream.

Preferably, the gas outlet opening is arranged at the height of a depositing plane for the substrates. Consequently, it can also be ensured that the gas supply unit generates an air cushion at the appropriate height, where subsequent substrates can slide on said air cushion in a friction-reduced manner against the abutments.

In particular, the gas outlet opening may be directed at a region between the first and the second abutment surfaces. This region is located in a corner of the tray, for example. Preferably, the first and/or the second abutment should be configured in such a manner that the gas stream may flow unimpaired past said abutments. This can be achieved, for example, in that the second abutment is at a sufficient distance from the first abutment such that the gas can flow through. Also, the second abutment could have holes, for example, or be configured as a wire bracket.

The gas supply unit may comprise a gas nozzle in order to increase the discharge speed of the gas stream, this potentially intensifying the friction-reducing effect on the substrates. Furthermore, the use of a gas nozzle makes it easier to achieve a desired direction of the gas stream.

In accordance with another exemplary embodiment, the gas supply unit comprises a blower. However, it is also possible to provide other devices that are capable of generating a gas stream.

In one exemplary embodiment, the second abutment is arranged so as to be perpendicular to the tray surface. Due to the resultant 90° angle between the second abutment and the tray surface there is no distortion perpendicular to the substrate transport direction in the substrate stack located on the tray. In this context, distortion is intended to mean an angle of the stack in the direction toward the second abutment of less than 90°.

In an alternative embodiment of the invention, the second abutment is vertically arranged. Such an arrangement of the second abutment has the advantage that the tray may be lowered vertically without increasing a distance to be traveled by the substrate up to the second abutment by lowering the tray.

For a simple design of the device, the second abutment may be fastened directly to the tray. In particular, the second abutment may be adjustably arranged on the tray. As a result of this, it is possible to adjust the abutment along a direction transverse to the sheet transport direction. Such an adjustment should be performed before the output of the substrates is started, said adjustment being a function of the format of the substrate that is used. The abutment may, in particular, be adjusted in such a manner that the path, which the substrate must slide transversely to the transport direction in the direction of the abutment, is minimized. As a result of a thusly minimized sliding path distance which the substrates must slide in the direction of the abutment, a considerable improvement of the stack accuracy transverse to the sheet transport direction can be achieved. In particular with narrow substrates that would have to slide correspondingly larger path distances when the abutments are non-adjustable, such an arrangement can have a positive effect.

The adjustment of the abutment may be automatically performed by motors or other electrical, or pneumatic actuators. Inasmuch as, usually, most system controls of modern printing machines contain information regarding the format width of the substrate to be printed, this enables the determination of path information for the abutment and can, subsequently, be automatically translated into an abutment position, without the intervention of an operator.

In order to ensure an efficient adjustment of the second abutment, the tray may comprise a linear guide for said abutment.

If, as mentioned above, the abutment is mechanically adjusted, it is possible to provide—in another exemplary embodiment—a setting wheel by means of which the position of the second abutment can be adjusted. The setting wheel may act on an axis that, in turn, acts—via a deflection—on the second abutment and thus adjusts said second abutment transversely with respect to the substrate transport direction.

In one embodiment of the invention, the lifting device lifts and lowers the tray parallel to the second abutment surface. This ensures that the distance to be traveled by the substrate up to the second abutment remains the same, even with increasing stack height. In the case of the second abutment arranged perpendicularly to the tray surface, such lifting or lowering results in a deviation of the lifting and lowering direction from the vertical.

In one embodiment of the invention, the first abutment may be part of a depositing member by means of which sheets are deposited on the tray. This may be, for example, a rear wall of a printing machine, said wall being below a substrate output where the substrate will come to abut.

In particular, the first abutment may be inclined in such a manner that it forms a right angle with an adjacent region of the tray surface. If the tray is subsequently lifted or lowered parallel to the first abutment surface, it is possible—in combination with a second abutment provided vertically on the tray—to produce a substrate stack which neither displays a distortion in substrate transport direction nor transversely with respect thereto; i.e., a 90° angle is formed in both directions.

In a further embodiment of the invention, the tray surface may comprise a first and a second depositing region, said regions each being tilted differently from the horizontal about the second axis. As a result of this, it can be avoided that, during output to the tray, the substrates must be transported at a too severely inclined tray surface. In contrast therewith, a larger incline of the tray surface is desirable in the first region of the tray surface because this facilitates the sliding of the substrates on the tray.

Furthermore, this can prevent a shifting of the substrates already present on the tray.

The object that is the basis of the invention is also achieved by a method for depositing sheet-shaped substrates, in particular printing materials, in a printing machine, wherein the sheet-shaped substrates are conveyed to a substrate support comprising a tray, and a first and a second abutment so as to form a stack. The tray is rotated about a first axis that is parallel to a substrate transport axis and about a second axis that is perpendicular to the first axis and parallel to a tray plane. The method comprises the lowering of the tray and the generating of a gas stream under a respective substrate that is being conveyed onto the tray, said gas stream being directed at a region between the first and the second abutments. In this method, the sheet-shaped substrates are transported against the abutments due to the tilt and the gas stream, an air cushion generated by the gas stream reducing the friction between the sheet-shaped substrate and the tray surface or between a sheet-shaped substrate and a substrate that is already located on the tray. By lowering the tray, a constant dropping height of the substrate to the tray surface or a substrate located there is being maintained.

Preferably, the tray is lowered parallel to the abutment surface of the second abutment. As a result of this, it is ensured that the distance of the path for the substrate up to the second abutment remains constant, despite lowering the tray. In one embodiment, the second abutment extends perpendicularly to the tray surface, which ensures a 90° angle of the substrate stack transverse to the substrate transport direction.

In an alternative embodiment of the invention, the second abutment is arranged vertically relative to a horizontal.

The first abutment may form a right angle with an adjacent region of the tray surface. Inasmuch as the tray surface is inclined relative to the horizontal, this causes the first abutment to also be inclined relative to the horizontal. Preferably, in this embodiment, the tray is lowered parallel to the first abutment surface, thus ensuring that the substrate stack displays an angle of 90° relative to the first abutment surface.

Hereinafter, the invention will be explained in greater detail with reference to the drawings. They show in

FIG. 1 a schematic side view of a stacker region of a printing machine comprising the inventive device for depositing a substrate;

FIG. 2 a schematic plan view of the device for depositing a substrate in accordance with FIG. 1;

FIG. 3 a schematic front view of the device for depositing a substrate in accordance with FIG. 1;

FIG. 4 a schematic perspective representation of the device for depositing a substrate in accordance with FIG. 1;

FIG. 5 a schematic plan view of an alternative device for depositing a substrate;

FIG. 6 a schematic perspective representation of the alternative device for depositing a substrate;

FIG. 7 a front view of the alternative device for depositing a substrate;

FIG. 8 a schematic, perspective representation of the alternative device for depositing a substrate; and

FIG. 9 a schematic side view of a printing machine comprising another alternative device for depositing a substrate.

Information regarding location or direction used in the description hereinafter primarily relates to the depictions in the drawings and should thus not be viewed as being restrictive. However, they may also relate to a preferred final arrangement.

FIG. 1 shows a schematic side view of a stacker region of a printing machine comprising a substrate output unit 1, a substrate depositing device 2, as well as a gas supply unit 3.

The substrate output unit 1 comprises a plurality of transport rollers 4 that are suitable to convey substrates 6 from a printing region of the printing machine in a substrate transport direction (from right to left in FIG. 1) as indicated by arrow A toward the substrate depositing device 2.

In accordance with a first embodiment shown by FIGS. 1 through 4, the substrate depositing device 2 comprises a tray 10 with a tray surface 8. The tray surface 8 comprises a first depositing region 12 located adjacent to the substrate output unit 1, and a second depositing region 14 located further away from the substrate output unit 1. As is obvious from FIG. 1, the first and the second depositing regions 12, 14 are inclined against the substrate transport direction A, relative to the horizontal, the first depositing region 12 being inclined more than the second depositing region 14. FIG. 3 shows that the tray surface 8 is also tilted about a first axis parallel to the substrate transport direction A, relative to the horizontal. This tilting of the tray 10 about the first axis is combined with the inclination of the first and second depositing regions, this corresponding to a tilting of the tray 10 about a second axis perpendicular to the first axis. As a result of this, the tray surface overall drops downward toward an edge 18, said edge forming the lowest point of the tray surface 8.

As is obvious from FIGS. 2 through 4, the tray surface 8 has an elongated recess 20 with a center strip 22, these extending along the substrate transport direction A. The recess 20, as well as the center strip 22, extend from an outer end of the tray 10, said end being remote from the substrate output unit, via the second region 14 into the first region 12 of the tray surface 8. On the one hand, the recess 20 facilitates the removal of a substrate stack and, on the other hand, said recess facilitates the transport of the substrate 6 over the tray surface 8.

As is also readily obvious from FIG. 2, an edge 24 is formed between the depositing regions 12 and 14, said edge extending transversely with respect to the substrate transport direction over the tray surface 8. Although the edge is shown in the figures as a cutting edge of two straight depositing surfaces 12, 14, said depositing surfaces may also be connected via a rounded part.

A first abutment 25 essentially extending in vertical direction—viewed in substrate transport direction A—is provided adjacent to the first depositing region 12 of the tray 10, which abutment 25 may be part of the substrate output unit 1 or the substrate depositing device 2. In the shown embodiment, the abutment 25 is a straight plate connected with the substrate output unit 1. Furthermore, a second abutment 26 is provided on the tray 10, said second abutment extending at a right angle relative to the first abutment 25 and to the tray surface 8. The second abutment 26 is configured as a wire bracket and fastened transversely with respect to substrate transport direction A in the region 12 of the tray surface 8. An adjustment may be performed, for example, by means of a not illustrated setting wheel that moves the second abutment along a not illustrated linear guide in the tray 10. The adjustment may be performed manually or also automatically by means of an appropriate drive and control unit. Alternatively, the second abutment 26 may be stationarily fastened to the tray 10. The second abutment 26 may also be configured as a stop baffle instead of as a wire bracket, said stop baffle being provided, for example, with gas passage openings.

In such an arrangement of the tray surface 8, a substrate stack consisting of a plurality of substrates 6 will form a right angle with the first and second abutments 25, 26 on the second abutment 26; however, said substrate stack will be distorted at the first abutment 25, i.e., the stack does not form a 90° angle in this direction. The reason for this is that the first abutment 25 and the depositing region 12 of the tray surface 8 form an angle that is smaller than 90°.

The tray 10 can be moved up and down by means of a not specifically illustrated lifting unit, with the movement occurring parallel to a plane of the second abutment 26, as is shown by double arrow B in FIG. 3.

Each of FIGS. 1 through 3 shows the gas supply arrangement 3 that is represented as a gas line element 30 (for reasons of simplification, it was left out of the drawing of FIG. 4). This gas line element is arranged laterally adjacent to the higher edge of the tray 10 and is permanently mounted to the substrate output unit 1. Alternatively, said gas line element could also be mounted to the substrate depositing device 2. The gas supply arrangement 3 comprises a gas supply that is not shown in the figures, said gas supply arrangement being able to supply gas to the gas line element 30. For example, a ventilator or a pressurized air connection of an external pressurized air source can be used.

On a free end, the gas line element 30 has a gas outlet opening in the form of a gas nozzle 34 that is arranged at the height of a depositing plane. In this case, the depositing plane is formed by the tray surface 8 for a first substrate 6 ejected by the substrate output unit 1. For all the subsequent substrates 6, the depositing plane is formed by the previously ejected substrate 6, respectively.

The gas nozzle 34 is essentially directed at a region between the first abutment 25 and the second abutment 26. In particular, the nozzle is inclined slightly downward, and the gas stream exiting from the nozzle 34 flows over the depositing plane in the direction of the lowest point of said plane in the region of the corner 18 of the tray 10. As a result of the fact that the second abutment 26 is arranged at a distance from the first abutment 25 and, furthermore, is configured as a wire bracket, the gas stream essentially flows off the opposite end of the tray without being obstructed.

FIGS. 5 through 8 show an alternative embodiment of a substrate depositing device 2. FIGS. 5 through 8 use the same reference signs as the first embodiment in accordance with FIGS. 1 through 4. The substrate output unit 1 and the gas supply unit 3, these also being provided in this embodiment, may have the same design as those that have been previously described, so that it is not necessary to describe them in detail. The gas supply unit 3 was left out in order to simplify the illustration in FIGS. 6 and 8.

Again, the substrate depositing device 2 comprises a tray 10 that is designed as previously described. In particular, the tray 10 has a tray surface 8 with first and second depositing regions 12, 14, each being inclined relative to the horizontal. FIG. 7 shows that the tray surface 8 is also tilted about a first axis parallel to substrate transport direction A, relative to the horizontal. As a result of this, the tray surface 8, overall, again slopes toward an edge 18, said edge forming the deepest point of the tray surface 8.

Again, a first abutment 25 is provided adjacent to the first depositing region 12 of the tray 10. Likewise, a second abutment 26 is provided on the tray 10. However, this abutment extends vertically and not perpendicularly with respect to the tray surface 8, as was the case in the first embodiment, this being particularly clear in FIGS. 5 and 7. As is readily obvious from FIG. 6, the second abutment 26 is located laterally on the tray 10. However, in this embodiment, too, the second abutment 26 may be arranged so as to be movable in the depositing region 12 or 14 of the tray surface 8. In particular, the second abutment 26 is arranged adjacent to a lower lying lateral edge of the tray 10. Said second abutment is shown as a solid metal sheet, however, it may also be configured as a wire bracket or as a perforated metal sheet.

Again, the tray 10 can be moved up and down by means of a not specifically illustrated lifting unit, the movement taking place parallel to a plane of the second abutment 26, i.e., vertically, as indicated by double arrow C in FIG. 7.

FIG. 9 shows another alternative embodiment of a substrate depositing device 2. In FIG. 9, the same reference signs are used as in the first embodiment in accordance with FIGS. 1 through 4. The substrate output unit 1 and the gas supply unit 3, which are also provided in this embodiment, may have the same design as those previously described, so that a further description thereof is not provided. In order to simplify the illustration in FIG. 9, the gas supply unit 3 was left off.

Again, the substrate depositing device 2 comprises a tray 10 that is designed as the one above and inclined toward a lowest point. Likewise, first and second abutments 25, 26 are provided, the second abutment 26 being designed in accordance with the first embodiment. However, said abutment could also have the design in accordance with the second embodiment.

The essential difference with respect to the first two embodiments is in the arrangement of the first abutment 25. The first abutment 25 is inclined in such a manner that it forms a right angle with the depositing region 12 of the tray 10. As a result of this, a stack of substrates on the tray 10 forms a right angle on its edge facing the first abutment 25, as well as on its edge facing the second abutment 26.

Again, the tray 10 can be moved up and down by means of a not specifically shown lifting unit, the movement following the inclination of the first abutment 25, as is shown by double arrow D in FIG. 9. At the same time, the up and down movement takes place parallel to a first plane of the second abutment 26.

Hereinafter, a method for depositing sheet-shaped substrates, in particular of printing materials, in a printing machine, so as to form a stack will now be explained in greater detail with reference to the figures and, in particular, to FIGS. 1, 3 and 9.

A substrate 6 is transported via transport rollers 4 of the substrate output unit 1 in substrate transport direction A into the region of the substrate depositing device 2. In particular, the substrate is conveyed so as to be above the tray 10 that is in a corresponding receiving position. After the transport rollers 4 have released the substrate 6, the substrate drops down onto the tray 10. The gas supply arrangement 3 generates a gas stream under the falling substrate, said stream being directed transversely and slightly counter to the substrate transport direction. This gas stream generates an air cushion between a depositing plane formed by the tray surface 8, or by a substrate 6 located on the tray, and the falling substrate 6.

Due to the double inclination of the tray 10 (counter and transverse to substrate transport direction A), the substrate 6 slides easily over the depositing plane in the direction of the first and second abutments 25, 26 and comes to abut against said abutments. The movement in the direction of the first abutment 25 and the second abutment 26 is also aided in the direction of the gas flow, with the air cushion preventing, or at least reducing, a friction between the depositing planes and the substrate. The gas stream may be used intermittently or also continuously.

In this manner, the substrates 6 may be deposited one after the other to form a stack on the tray. After each substrate 6, or after a specific number of substrates 6, the tray 10 is lowered by the lifting device along the first abutment 25 and parallel to an abutment surface of the second abutment 26. Depending on the arrangement of the first and second abutments 25, 26, the tray 10 is lowered in vertical direction or in an inclined manner.

The inclined lowering of the tray 10 in conjunction with the second abutment 26 positioned perpendicularly to the tray surface 8 ensures, in so doing, that a sliding path of the substrate 6 out of a position it is in immediately upon the release by the substrate output unit 1, toward the abutments 25 and 26 remains essentially constant, even after lowering the tray 10.

Due to the ejection of the plurality of substrates 6 onto the tray 10, a substrate stack is formed on the tray surface 8, said substrate stack forming an angle with said tray depending on the arrangement of the second abutment 26, said angle being either 90° (first embodiment) or smaller than 90° (second embodiment).

The lowering of the tray 10 along the first abutment 25 takes place depending on the arrangement of the first abutment 25, likewise vertically or inclined. If, as is shown by FIG. 1, the first abutment 25 and the tray 10 form an angle that is smaller than 90°, the tray 10 is lowered in vertical direction; whereas, if the first abutment 25 is arranged at a right angle relative to the tray 10, as shown by FIG. 9, the tray 10 is lowered at an inclination along the first abutment 25.

A substrate stack that was produced on the substrate depositing region 2 in accordance with FIG. 9 thus does not display any distortions. This means that the substrate stack forms a 90° angle relative to the first abutment 25, as well as relative to the second abutment 26.

Hereinabove the invention was described with reference to specific embodiments without being restricted to a specifically represented form. In particular, it is possible to combine features of an embodiment with features of another embodiment, or to interchange certain features, in so far as compatibility has been provided. 

1. Device for depositing sheet-shaped substrates in a printing machine so as to form a stack, the device comprising: a tray for receiving the substrates, the tray having a tray surface that is tilted about a first axis and about a second axis, relative to a horizontal; a lifting device for lifting and lowering the tray; a first abutment having a first abutment surface; and a second abutment having a second abutment surface, with the first and the second abutment surfaces being arranged so as to be perpendicular to each other, and with substrates deposited on the tray coming to abut against the first and the second abutment surfaces due to the tilting of the tray surface, wherein the lifting device is arranged in such a manner that the lifting device lifts and lowers the tray parallel to the second abutment surface.
 2. The device according to claim 1, wherein the first axis is parallel to a printing material transport axis, and the second axis extends perpendicularly to the first axis and is in a plane parallel to the tray surface.
 3. The device according to claim 1, wherein the second abutment is arranged so as to be perpendicular to the tray surface.
 4. The device according to claim 1, wherein the second abutment is vertically arranged.
 5. The device according to claim 1, wherein the second abutment is fastened to the tray.
 6. The device according to claim 1, wherein the second abutment is adjustable.
 7. The device according to claim 6, wherein the tray includes a linear guide for the second abutment.
 8. The device according to claim 6, wherein a setting wheel is provided, by means of which the second abutment can be adjusted.
 9. The device according to claim 1, wherein the second abutment is configured as a wire bracket.
 10. The device according to claim 1, wherein the first abutment is part of a depositing member by means of which the substrates are deposited on the tray.
 11. The device according to claim 1, wherein the first abutment is inclined in such a manner that it forms a right angle with an adjacent region of the tray surface.
 12. The device according to claim 11, wherein the lifting device lifts and lowers the tray parallel to the first abutment surface.
 13. The device according to claim 1, wherein the tray surface comprises a first and a second depositing region, the regions being each tilted differently from the horizontal about the second axis. 